Hi and welcome,
There are some great links in the sticky at the top of the page. Located here http://www.thecatsite.com/forums/showthread.php?t=74659
Its full of great advice and will really help you with the basics.
You can usually feel the kittens start to move around 3 weeks before your cat is due.
Has she been nesting at all?
Does she have a room she can be in by herself with a nesting box all set up for her? Confining her to one room will help keep her feeling safe and secure. This will help her now and also after the babies have arrived as mom's will move their babies around if they dont feel safe.
Is she on a good quality kitten food? She will need all the extra calories and goodness this has to offer from now up until she has finished nursing the kittens.
Have you noticed her becoming restless? eating less? or having an upset stomach. These are all sighs labour could be coming soon.
Usually 24/48 hours before labour you may notice a brown discharge. This is the mucus plug that most cats will loose close to birth.
One last thing. If she is an indoor/outdoor cat she needs to be strictly kept indoors now. Not only is it safest for her during her pregnancy but it is also possible for cats to become pregnant again within a few days of giving birth so she needs to be kept away from any intact males until she can be spayed. This an usually be done from about 8 weeks after the kittens are born.
I hope this helped a little. A great thing about this site is that you can be sure there will be lots more advice to come.
Emma x x